Shading for water stress mitigation in Copaifera langsdorffii Desf. seedlings

Abstract In this study, we hypothesized that Copaifera langsdorffii Desf. seedlings do not tolerate cultivation under water deficit, but shading could minimize stressor effects of water shortage and enable fast antioxidant responses, maintaining high photosynthetic rates and favoring stressed plant recovery. Therefore, we evaluated gas exchange and antioxidant activity of C. langsdorffii seedlings submitted to intermittent water deficit and different shading and their potential for metabolic recovery after re-irrigation. Seedlings were grown under 0, 30, and 70% shading and under continuous and intermittent irrigation. The plants were evaluated at the beginning of experiment, first and second zero photosynthesis, first and second recovery, and the end of experiment. Seedlings under intermittent irrigation and 0% shading could not recover their photosynthetic metabolism at the end of experiment, showing a marked decrease in rubisco carboxylation efficiency (A/Ci) and increase in antioxidant activity. Yet, seedlings grown under shading and intermittent irrigation could recover their photosynthetic metabolism, without permanent changes and/or damages to photosystem II efficiency, proving our hypothesis.